Device for demonstrating improper lifting practices



H. M. KISTLER ETAL.

DEVICE FOR DEMONSTRATING IMPROPER LIFTING PRACTICES Filed Aug. 9, 1951 V INVENTOR.

HOWARD M. K/STLER WILLIAM H. K/STL ER ATTORNEY DEVICE FOR DEMONSTRATING IlVlPROPER LIFTIN G PRACTICES Howard Milton Kistler and William Henry Kistler, East Orange, N. J.

Application August 9, 1951, Serial No. 241,088

14 Claims. (Cl- 35-29) This invention'relates to visual aid demonstration lifting devices, and more particularly, to demonstration devices of the above type which may be used by lecturers and instructors to dramatically illustrate improper lifting practices.

i In industry there is a high incidence of lost time resulting from back injuries caused by improper lifting of heavy objects with the back rather than the strong leg muscles. Many employers, realizing that these injuries are caused by ignorance of proper lifting practices, and can, therefore, be avoided, have made available to their employees, especially those doing heavy work, safety instruction courses emphasizing among other things, the importance of keeping the back straight or nearly vertical and bending the knees while lifting heavy objects. These safety instruction courses have been found to pay dividends to employers, and, hence, they are rapidly gaining popularity.

. The present invention is directed to a mechanical demonstration device, representing a man, which is made essentially like the human body in its general structure and illustrating the weak back muscles attached to and joining the vertebrae, as well as the fact that little or no stress is placed on the back muscles in correct lifting, whereas such strains do exist in incorrect lifting. Other requirements of such demonstration devices are that they must be of such size, weight and form to permit ready transport throughout industrial plants for instruction purposes, be satisfactory in operation so as not to detract from dramatic demonstration, and be substantially built and thus durable.

One such demonstration figure has heretofore been proposed and is satisfactory to a high degree. The present invention, however, is aimed primarily at refinements and improvements over the previously proposed device which will greatly increase its usefulness. Illustrative of some of the highlights of the present improvements are the ability to lift varying loads and to demonstrate the harmful effects of the heavier loads, the ability to stand in upright position without manual support, limited movementof the joints to coincide with the actual movements of the corresponding joints of the body which they represent, and means to actually indicate the degree of strain under different types of lifting.

These, as Well as other features and improvements, will be shown and described in the accompanying drawings and the detailed description which follows.

Referring to the drawings- Fig. 1 is a right side elevation of the demonstration lifting device;

Fig. 2 is a rear view of Fig. 1;

Fig. 3 is a right side view showing the manner of.

demonstration;

Fig. 4 is a right side view of the lower portion of the device in a sitting or squatting position;

Fig. 5 is a front view, partly in cross section, of the manner of connection of certain of the parts;

Fig. 6 is an enlarged side view of part of one of the leg segments.

Referring to the drawings, the demonstration lifting device is constructed on a platform or base 1 and is com prised generally of a head portion 2, a shoulder block 3 to which the head portion is mounted, a pair of arms 4 pivotally mounted to the shoulder block, a hip block 5, a series of vertically disposed rectangular blocks 6 connecting the shoulder and hip blocks and representing the spine or vertebrae, a pair of segments 7 representing the upper portion of the legs and pivotally connected to the hip blocks, a pair of segments 8 representing the lower portion of the legs and pivotally connected to the upper leg segments 7, and a pair of foot blocks 9 firmly mounted to the top of the platform.

The demonstration device heretofore proposed includes generally the above parts, although not in the same form or construction, and, therefore, the above parts, in themselves, do not constitute the present invention. The present invention, rather, is directed to refinements, improvements, additional features, and especially a novel manner of construction which greatly improves the operation, utility and realistic and dramatic eifect of the device.

Turning now to a complete description of the present invention, the blocks 6 are bound together at the front and back, at the front by a thin, flexible webbed strap 10 and at the back by two vertical rubber strips 11. Both the webbing 10 and the rubber strips 11 should extend continuously from the shoulder block 3 to the hip block 5, binding not only the blocks 6 together, but the said blocks to the shoulder and hip blocks as well. The webbing 10, being flexible, permits the blocks to separate at the rear, the rubber strips 11 stretching, and thus lets the spine curve realistically to the front substantially as in the human body. If tacks are used to attach the webbing, care should be taken to place them sulficiently close together to prevent any displacement,

other than angular movement, of the blocks with respect;

to one another, otherwise, the spine will bend at one place instead of curving.

The rubber strips 11 are tacked at the back and serve to demonstrate the stretching which occurs in the weak back muscles when the back is bent.

To permit the blocks 6 to adequately support the shoulder blocks, as well as the parts attached thereto, to lift reasonable weights, and to prevent damage and excessive strain to the rubber strips, two tension springs 12 are anchored to the shoulder block, pass through holes in the back blocks 6 and are secured, at their lower ends, to the hip block 5.

A hollowed head, generally designated by the reference numeral 2, is secured to the top of the shoulder block. The head contains a pulley 13 fixedly mounted on a shaft, which shaft is rotatably secured between parallel profile members 2a of the head. The ends of the shaft extend through the profiles, and to each end of the shaft is fastened a pointer or needle 14. As shown in Figs. 1 and 3, the pulley is acted upon by a tension spring 15 which normally tends to rotate the pulley in a counterclockwise direction. However, the rotation of the pulleyby the spring is normally resisted by a wire or cord 16 which passes freely through holes in the shoulder block 3, the series of blocks 6 and is anchored to the hip block 5. Preferably, the wire is to the rear of the above-mentioned blocks, so that, when the back is bent and the rear ends of the blocks 6 separate (see Fig. 3), the wire will cause rotation of the pulley against the tension of the spring, moving the pointers 1a with respect to the scales 17. The scales are divided into safe and unsafe regions, indicated by green and red, respectively. The degree of deflection of the pointer from the norm measures the extent to which the back is bent. Thus, undue stretching of the rubber bands 11, representing the back muscles, or undue separation of the blocks 6, representing the spine, will cause the pointers 14 to indicate a dangerous condition. When the back or spine straightens up, the pointers are returned to the safe region by the spring 15.

The arms 4 are made of A" tempered Masonite because of its freedom from warping and changes in shape from moisture absorption. They are secured to the shoulder block 3 by machine screws 18. The holes in the arms through which the screws pass are reinforced with brass grommets to assure free rotation and to prevent excessive wear.

A small wooden .box 19 is pivotally attached to the lower ends of the arms 4 (corresponding to the hands). Variable weights'may be placed in the box and lifted to show strain on the spine and back muscles under varying loads and different methods of lifting.

The upper and lower legs 7 and 8, respectively, are likewise madeof tempered Masonite; The upper legs are pivotally attached to the hip block by screws 20 in the same manner that the screws 18 are attached to the shoulder block..

Protrudingfrom. each. side: of thehip block 5 are small dowels or pins: 2 1, and. the protruding ends thereof travel? in circular grooves 22. The: length of the grooves 22' determines the extent tcr which the? upper legs; 7 can. pivot with. respect to:- the' hip block 5. As; shown in Fig. l, the dowels Z'll occupy: clockwise positions at. the. right ends. of the grooves 22 when the demonstration figure is standing upright,v whereas the dowelsv occupy counterclockwise positions at the left ends of the grooves: ('as viewed in. Fig; 4-): when the figure assumes a. sitting or squat position. Thus, as; in. the human body, the trunk may bend: forwardly from. the hips, but: not. backwardly;

A similar arrangement is employed to restrain the. movement of the knee joints so that they will only bend forwardly in one direction. (as shown in Fig. 4), as in the human body; The upper ends. of the lower legs 8 are pivotally connected by brass bushings 23 (see Fig. 5) held in place by screws 23a and wing nuts 23b. The upper ends of the lower legs 8 are provided with inwardly depending dowels or pins 24 which, like the pins 21, travel in circular grooves 25 formed in outer sides of the lower ends of the legs 7'. As viewed in Figs. 1' and 3, the rightward ends of the circular grooves 25 are provided with vertical upward extensions 2521 so that when the legs are straight (Fig. 1-) the upper legs 7' are permitted to drop downwardly, the dowels 24 entering the extensi'ons 25a, into a locked position. Accordingly, the holes 26 (Figs. 3, 5' and 6) through which the bushings 23 and screws 23a pass are elongated in order to permit the relative movement of the upper leg 7 with respect to the lower leg 8 necessary for locking. As shown in Fig. 4, the: leftward or counterclockwise end of the groove 25 limits the amount of permitted knee bend to correspond to. the maximum knee bend possible in the human body. When in the locked position, to rotate the legs at the knee joint it is necessary merely to lift the upper legs until the dowels 24 reach the circular grooves 25; the knee joint may then be bent to the extent permitted by the said circular groove 25.

The lower ends of the lower legs 8 are pivotally connected by screws 27 in vertical slots of the foot blocks 9. The foot blocks, as explained, are rigidly secured to the top of the base 1'. A small block 28 may be positioned on the base I to serve as a seat for the figure.

It is desirable that the device be constructed so that it may stand upright for dramatic effect without any danger of falling backwardly. If permitted to fall backwardly not only would much of the realism be lost, but in addition the demonstrator could be hurt. Toward this end, the lower end (i. e., the ankle) of the lower leg 8 is cam shaped to permit counterclockwise rotation of the leg with respect to the foot 9, but the contour of the rearward or heel portion 29 of the leg 8 limits the rotation of the leg, 8 to approximately the vertical position (see Fig. l) by engaging or leaning against the lower end of the slot. In fact, it may be desirable that the heel portion 29 permit the leg to lean slightly backward of the vertical position (but not further) to aiford greater balance to the figure when standing in the upright position, or, in other words, to insure that the center of gravity is rearwardly ofisct, that is, somewhat to the right, as viewed in Fig. 1, of the pivot screws 27.

The manner of locking the upper and lower legs 7 and 8, respectively, by permitting the dowels 24 to enter the upright extensions 25a of the grooves 25 has been described above.

Finally, in order that the figure may stand upright, it is necessary to prevent relative rotation between the hip blocks 5 and the upper legs 7. This is accomplished, as shown in Fig. 2, by a small pivotal latch 30 attached to the rear of the hip block and a cooperating notch or slit in the said leg 7. The latch 30 may be swung in the direction of the arrow, out of operative engagement with the notch when relative movement or rotation is desired.

The control of the device for purposes of demonstration is accomplished by a handle 31 attached to the rear of the hip block 5'. Assuming. that the figure is standing in the upright position, the latch 30 may be unlocked and the handle lifted to unlock the dowels 24. The figure 4 may then be put in the erect sitting position, shown in Fig. 4. A suitable weight may be placed in the box, and the handle lifted, keeping the back vertical. In such lifting, since all the strain is on the leg muscles, the back does not bend (unless, of course) the weight is so heavy that it would be dangerous to lift in any manner whatsoever). Also, the pointer hands 14 do not deflect, indicating, that. the back muscles. are not being strained.

Improper lifting practices. can be demonstrated by looking the legs 7 and 8, or bending them somewhat as most people do, and bending the. trunk forward from the hips, the arms hanging; straight down. With a weight placed in the box, the hips may be rotated, using the handle 31 to lift the trunk to the vertical position, as indicated in Fig. 3. During such lifting, the blocks 6 separate at the rear, andthe rubber bands 11 stretch, demonstrating strain on the spine and back muscles, and, if the weight is sufficiently heavy, the pointer hands 14 will deflect into the red or danger zone of the scale 17.

Obviously, in the same manner, demonstrations of proper and improper methods of lowering heavy objects can be given. Also, various other lifting practices can be demonstrated.

The. invention has been shown in only a single preferred form and by way of example, but obviously; many variations and modifications: may be made therein and in its mode of application which will still be within the spirit of the. invention. It is to be understood, therefore, that the. invention is not to be limited to any specific form or embodiment, or in any other respect, except insofar assuch limitations are specified in the appended claims.

Having thus describedmy invention, what I claim is:

l. A demonstration lifting device capable of standing: upright comprising a body portion, pivotal upper leg segments attached to the body portion, lower leg seg ments pivotally attached at one end to the upper leg" segments and at the other to a base, locking means to prevent the pivotal movement between the upper leg segments and the body portion, and locking means to prevent pivotal movement of the lower leg segments with. respect to the upper leg segments.

2. A combination according toclaim 1 characterized by the fact that the center of gravity of the device in the upright standing position is offset rearwardly with respect to the lower pivots of the lower leg segments, the contour of the lower ends of the lower leg segments preventing pivotal movement between the said seg-- ments and the base when the center of gravity is so located.

3. A combination according to claim 1 wherein the locking means to prevent pivotal movement between, the body and the upper leg segments includes a movable latch associated with one of said members and a notch adapted to be engaged thereby associated with the other of said members.

4. A combination according to claim 1 wherein the: locking means to prevent pivotal movement between the upper and lower leg segments includes a pinor dowel associated with one of said members which is adapted to engage a slot associated with the other of said members, the Weight of the device supported by the body portion serving to maintain the engagement.

5. A demonstration lifting device comprising a body portion including a series of vertically disposed blocks, attached at their front ends but capable of separation at their rear ends under strain, pivotal arm, and leg members attached to said body portion representing the correspond.- ing parts of the human body, an indicator, and. means for deflecting said indicator in accordance with the amount of separation of the blocks.

6. A combination according to claim 5 wherein therear ends of the blocks are connected by a yieldable band representing the muscles of the back.

7. A demonstration lifting device comprising a body portion including a series: of vertically disposed blocks, attached at their front ends but capable of separation at their rear ends under strain, a head. portion. attached to said body portion, pivotal arm andv leg members. attached to said body portion representing the corresponding parts of the human body, a rotatable spring-urged pointer mounted to the head portion, and a flexible, but not yieldable, strand passing through the said. blocks and acting against thev spring. to deflect. the pointer inaccordance with the degree of strain indicated by the separation of the blocks.

8. A combination according to claim 7 including a scale marked 01f to show safe and unsafe strains.

9. A combination according to claim 7 including a rotatable wheel or pulley attached to the head, said pointer being attached to the wheel, and said wheel being acted upon by a spring in one direction and by the strand, when the blocks are separated under strain, in the other direction.

10. A demonstration lifting device comprising a body portion, upper leg segments attached to the body portion, lower leg segments pivotally attached to the upper leg segments, one of said leg segments containing an elongated slot at the pivot to permit limited relative translatory movement between the leg segments, and means for controlling the movement of the upper segment with respect to the lower segment substantially in accordance with the permissible movement of the corresponding parts of the human body, which means includes a pin or dowel independent of the pivotal connection associated with one of the segments which is adapted to travel in a curved guide associated with the other of said segments, and a substantially vertical offshoot extension of said guide into which the dowel may be inserted when the segments are in the vertical standing position to prevent pivotal movement between the segments.

11. A combination as set forth in claim 10 including a base, foot blocks mounted thereon to which the lower ends of the lower segments are pivotally attached, the contour of the lower ends serving to prevent pivotal movement of the lower leg segments substantially behind the vertical position, but not interfering with the forward pivotal movement thereof.

12. A device for demonstrating lifting practices comprising two pivotally joined members representing parts of the human body connected by joints, the pivot hole of one of the members being enlarged to permit relative translatory movement between the members, a dowel or pin independent of the pivot, a companion curved guide for the dowel, the length of the guide determining the extent of the pivotal movement between the members, and an offshoot extension of said guide into which the dowel may be directed because of the permissible relative movement between the members in order to prevent pivotal movement between the members.

13. A device for demonstrating lifting practices comprising two pivotally joined members representing parts of the human body connected by joints, the pivot hole of one of the members being elongated to permit relative movement between the members, a dowel or pin independent of the pivot associated with one of the members, a curved guide for the dowel concentric with the pivot and associated with the other of the members, the length of the guide determining the extent of the pivotal movement between the members, and an offshoot extension of said guide disposed in substantially the same general direction as the elongated pivot hole to permit the dowel to be guided into the extension for the purpose of locking the members together.

14. A combination, according to claim 13, wherein the elongated slot and the offshoot extension of the guide are substantially vertically disposed and the dowel is adapted to enter into the offshoot extension by gravity.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 514,620 Fuller Feb. 13, 1894 1,308,816 Smith July 8, 1919 2,118,093 McCue May 24, 1938 2,121,212 Ramsdell June 21, 1938 2,197,975 Fleet Apr. 23,1940 2,506,001 Sturman May 2, 1950 2,507,768 Champagne May 16, 1950 2,537,573 Conschafter Jan. 9, 1951 FOREIGN PATENTS Number Country Date 127,696 Germany Jan. 29, 1902 

